铝酸钙熔体结构的分子动力学模拟研究

采用分子动力学模拟研究了xCaO-(1-x)Al_2O_3(x代表成分的变化)高温熔体中Al的配位数及其两性、微结构单元分布等结构性质。在采用BMH势函数的基础上,将计算所得的Al-O、Ca-O和O-O的偏径向分布函数的第一峰的位置(1.76、2.34和2.91)以及Al、Ca的配位数与X射线衍射实验(1.765、2.36和2.885)及中子散射实验(1.759、2.337和2.898)进行比较,吻合很好,证明模拟非常成功,然后在此基础上,发现Al在体系中主要起阿格形成子的作用,其微观结构单元呈四面体结构,也就是说,Al的平均配位数为4,这一点与硅酸盐中Si-O的结构单元非常相似,在统计了平衡时微结构单元Q_i的分布之后,总结了铝酸钙熔体的微观结构单元分布随宏观组分变化的规律。

Molecular Dynamics Study of the Structure of Calcium Aluminate Melts

The microstructure of high- temperature xCaO-(1-x)Al2O3 melts was studied by the molecular dynamics simulation. By comparing the positions of first peaks of partial radial distribution functions between Al and O, Ca and O, O and O, and the coordination numbers of Al and Ca with the corresponding experimental data of X-ray diffraction and neutron scattering, which agree very well with each other, the simulation is proved very successful. Based on the verification, it was found that Al playes the roll of network former in the calcium aluminate melt. That's to say, the average coordination number of Al is 4 and tetrahedron is the main structural unit in calcium aluminate just as the action of Si in silicate melts. In the meantime, the distribution of 5 kinds of tetrahedrons Qi was counted and then the regulation of the changing microstructure of calcium aluminate melt following with the composition was analyzed. With the analysis of the number of next nearest neighbor around the centering atom Al and the examination of the snapshot, 3-coordinated oxygen and charge-balanced bridging oxygen were found to be the explanations of the phenomena of redundant charge and location of the cation Ca2+.